I gather @runneals has also had this. Writing (truncating) to an ArcGIS Online feature service (that was created by FME) fails with the following error.
WARN |ArcGIS Online Feature Service Writer: 'addResults' error for a feature in 'MAP_WS_POINT'. The error code from the server was '1000' and the message was: 'The type initializer for '' threw an exception.' 2021-01-25 23:34:13| 24.4| 0.2|WARN |... Last line repeated 999 times ... 2021-01-25 23:34:13| 24.4| 0.0|ERROR |ArcGIS Online Feature Service Writer: 10000 features successfully written to 'MAP_WS_POINT', but the server rejected the 1000 features in the last request due to errors
Anyone else getting this? Have asked our vendor but just posting here for wider visibility. It came up for the first time last night.